[Bug c++/50207] New: G++ segv's on reduced test case

[Bug c++/50207] New: G++ segv's on reduced test case

[bergner at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

             Bug #: 50207
           Summary: G++ segv's on reduced test case
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: bergner@gcc.gnu.org


A G++ from today's trunk (20110826) segv's on a reduced test case (using delta)
like so:

bergner@igoo:~> cat minimal.ii 
typedef long unsigned int size_t;
namespace std __attribute__ ((__visibility__ ("default")))
{
  using::size_t;
}

typedef unsigned char uint8_t;
namespace std
{
  namespace decimal
  {
    template < class _Fmt > struct _FmtTraits;
    class decimal32;
  }
}
namespace std
{
  namespace decimal
  {
    template <> class _FmtTraits < decimal32 >
    {
      public:
      static const std::size_t _NumBytes = 4UL;
    };
    template < class _Tr > class _DecBase
    {
      uint8_t _Bytes[_Tr::_NumBytes];
    };
    class decimal32:public _DecBase < _FmtTraits < decimal32 > >
    {
      decimal32 () { }
    };
  }
}
bergner@igoo:~> /home/bergner/gcc/install/gcc-mainline-debug/bin/g++ -Wall -S
minimal.ii 
g++: internal compiler error: Segmentation fault (program cc1plus)
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

GDB show this backtrace:

#0  0x0000000010412cc8 in decl_is_template_id (decl=0xfffb6edcc18,
template_info=0xfffb6edcc18)
    at /home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:267
#1  0x000000001041b44c in write_nested_name (decl=0xfffb6e24ac0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:928
#2  0x000000001041ab48 in write_name (decl=0xfffb6e24ac0, ignore_local_scope=0)
at /home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:855
#3  0x00000000104284e4 in write_class_enum_type (type=0xfffb6edd4a0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2398
#4  0x0000000010424840 in write_type (type=0xfffb6edd4a0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:1884
#5  0x000000001042d1ec in write_template_arg (node=0xfffb6edcc18) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2843
#6  0x0000000010428868 in write_template_args (args=0xfffb6f13a70) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2427
#7  0x000000001041b50c in write_nested_name (decl=0xfffb6e245b8) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:932
#8  0x000000001041ab48 in write_name (decl=0xfffb6e245b8, ignore_local_scope=0)
at /home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:855
#9  0x00000000104284e4 in write_class_enum_type (type=0xfffb6edccc0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2398
#10 0x0000000010424840 in write_type (type=0xfffb6edccc0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:1884
#11 0x000000001042d1ec in write_template_arg (node=0xfffb6edccc0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2843
#12 0x0000000010428868 in write_template_args (args=0xfffb6f14088) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2427
#13 0x000000001041b50c in write_nested_name (decl=0xfffb6e24ac0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:932
#14 0x000000001041ab48 in write_name (decl=0xfffb6e24ac0, ignore_local_scope=0)
at /home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:855
#15 0x00000000104284e4 in write_class_enum_type (type=0xfffb6edd4a0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2398
#16 0x0000000010424840 in write_type (type=0xfffb6edd4a0) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:1884
#17 0x000000001042d1ec in write_template_arg (node=0xfffb6edcc18) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2843
#18 0x0000000010428868 in write_template_args (args=0xfffb6f13a70) at
/home/bergner/gcc/gcc-mainline-base/gcc/cp/mangle.c:2427
...

The backtrace also show we have 10's of thousands of frames stacked repeated
over and over, so it looks like we've gone into some type of infinite
recursion.  A quick look at GCC 4.6 show's it fails in the same manner.  I
haven't checked anything earlier.

[Bug c++/50207] G++ segv's on reduced test case

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-08-27 04:48:41 UTC ---
Related to Bug 46862.

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.0
            Summary|G++ segv's on reduced test  |[4.7 Regression] G++ segv's
                   |case                        |on reduced test case

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-08-29
                 CC|                            |jakub at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-29 10:04:09 UTC ---
Caused by http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=177647

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-29 10:05:34 UTC ---
Oops, sorry, that was for PR50208.

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-29 11:18:10 UTC ---
I'd say this is invalid, TYPE_TRANSPARENT_AGGR is an ugly hack and we should
perhaps limit it just to scalar fields.

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-29 12:48:10 UTC ---
Created attachment 25125
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25125
gcc47-pr50207.patch

Untested patch which adds that limitation.  <decimal/decimal> still seems to
work.

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |jason at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> 2011-08-29 14:59:43 UTC ---
The problem here is not that the first field is aggregate, but that the first
field is a fake field for the base class.  I'll adjust the patch accordingly.

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> 2011-08-30 04:30:56 UTC ---
Author: jason
Date: Tue Aug 30 04:30:42 2011
New Revision: 178276

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178276
Log:
    PR c++/50207
    * class.c (finish_struct_1): Complain if the first field is
    artificial.

Added:
    trunk/gcc/testsuite/g++.dg/dfp/base.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/class.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #8 from Jason Merrill <jason at gcc dot gnu.org> 2011-08-30 04:37:23 UTC ---
Fixed.

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> 2011-08-30 21:48:38 UTC ---
Author: jason
Date: Tue Aug 30 21:48:34 2011
New Revision: 178343

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178343
Log:
    PR c++/50207
    * class.c (finish_struct_1): Complain if the first field is
    artificial.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/g++.dg/dfp/base.C
Modified:
    branches/gcc-4_6-branch/gcc/cp/ChangeLog
    branches/gcc-4_6-branch/gcc/cp/class.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug c++/50207] [4.7 Regression] G++ segv's on reduced test case

[bergner at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50207

--- Comment #10 from Peter Bergner <bergner at gcc dot gnu.org> 2011-09-08 18:09:02 UTC ---
Author: bergner
Date: Thu Sep  8 18:08:53 2011
New Revision: 178703

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178703
Log:
gcc/
    Backport from mainline

    2011-08-23  Jakub Jelinek  <jakub@redhat.com>

    PR c++/46862
    * class.c (finish_struct_1): If TYPE_TRANSPARENT_AGGR is set on a type
    which doesn't have any fields, clear it and diagnose.

    2011-08-29  Jakub Jelinek  <jakub@redhat.com>
            Jason Merrill  <jason@redhat.com>

    PR c++/50207
    * class.c (finish_struct_1): Complain if the first field is
    artificial.

gcc/testsuite/
    Backport from mainline
    2011-08-23  Jakub Jelinek  <jakub@redhat.com>

    PR c++/46862
    * g++.dg/dfp/nofields.C: New test.

    2011-08-29  Jakub Jelinek  <jakub@redhat.com>
            Jason Merrill  <jason@redhat.com>

    PR c++/50207
    * g++.dg/dfp/base.C: New test.

Added:
    branches/ibm/gcc-4_5-branch/gcc/testsuite/g++.dg/dfp/base.C
    branches/ibm/gcc-4_5-branch/gcc/testsuite/g++.dg/dfp/nofields.C
Modified:
    branches/ibm/gcc-4_5-branch/gcc/ChangeLog.ibm
    branches/ibm/gcc-4_5-branch/gcc/cp/class.c
    branches/ibm/gcc-4_5-branch/gcc/testsuite/ChangeLog.ibm